1. Field of the Invention
This invention relates to a device for recording information of a photosensitive material, and more specifically to a device for optically recording on a photosensitive material information to be read with an optical reading means. This invention is particularly directed to a device for preparing a kind of optical memory in which information is stored in an optically recognizable form on a disc of photosensitive material.
Magnetic memories such as the magnetic core, the magnetic drum, the magnetic disc and the magnetic tape memories have heretofore been used as computer information storage elements. These magnetic memories are not always advantageous in the field of information processing, particularly in the field of compact information retrieval devices. In this field, the conventional magnetic memories are disadvantageous in that they are of high price and small storage capacity and that the retrieval device which uses such a magnetic memory has large dimensions and is difficult to operate and maintain. Further, there is often desired a memory which retains information permanently so that information once recorded in the memory can be read out but new information cannot be put therein.
One of the information recording media which are used for the above described purpose is an optical memory which carries optical information on a rotatable disc and from which the optically recognizable information is read without bringing a reading element into contact with the surface thereof. Such an optical memory is advantageous in that the information recorded therein is not easily extinguished or damaged, and that duplication of the information can be simply performed through a photographic reproduction method. Owing to the simplicity of duplicating the information, the optical memory can be produced at a fairly low cost in comparison with the above mentioned magnetic memories.
The optical memory prepared by the device in accordance with this invention is, for instance, a photosensitive material in the shape of a disc which can be rotated in a turntable and the information recorded thereon is read by use of light rays passing through the disc and a photoelectric element which receives the light rays passing through the disc. The optical memory which is prepared by the device of the present invention is small in size and can be manufactured at a low cost, and accordingly, is suitable as a storage means for an automatic retrieval device used in connection with a microfilm reader.
The optical memory as described above to be prepared by the device in accordance with this invention should, of course, be capable of carrying as much information as possible. Therefore, it is necessary to record on the disc a number of binary black and white signal patterns which are as finely and accurately arranged as possible. The present invention is therefore directed to a device for recording optical information on a photosensitive material in a predetermined format very finely and accurately.
2. Description of the Prior Art
In order to record optically recognizable binary patterns on a photosensitive material, it has heretofore been known in the art to first convert the information to be recorded into binary signals and convert the binary signals to black and white patterns and then draft the patterns in an enlarged scale on paper. Then, the drafted patterns made on the paper in an enlarged scale are photographically recorded on a photosensitive material such as a photographic plate or film in a reduced scale.
The above described method of preparing the optical memory is disadvantageous in that the time of preparation increases as the amount of information to be recorded increases and the rate of occurrence of deviation in the position of the patterns also increases. Further, the above described method is complex in its check process and is limited in its recording density. For instance, preparation of an optical memory having a capacity of about 50 Kbits requires two persons working for about 200 hours. Besides, checking the prepared optical memory for errors by comparison with the drafted original patterns is very troublesome work.
It has also been known in the art to record black and white patterns on a disc in the field of the binary coded encoder which is used to detect an angle of rotation. However, the binary coded encoder is only required to carry periodically repeated patterns to provide a signal corresponding to the angle of rotation of the disc. Therefore, it is impossible to record at will various kinds of letters, numerals and figures in the coded patterns in accordance with this art.
Thus, there is a demand for an optical information recording device which makes possible automatic recording of the optical information in a short time and with high accuracy. Further, there is a demand for a device for recording optical information on a photosensitive material in which the error check of the recording can easily be conducted.